This invention is related to the invention disclosed in U.S. Pat. No. 3,986,261 of Frank R. Faunce, and constitutes an improvement over the teachings thereof. Dental veneers have been manufactured and sold in accordance with the teachings of the above noted patent. These laminate veneers have been manufactured by molding a single mass of polymer resin suitable for bonding to the enamel surfaces of the patient's teeth. These laminate veneers have also been provided with a uniform color system dispersed throughout the thickness of the laminate veneer. It has been determined that dense polymer materials do not ordinarily have the capability of efficient bonding to a patient's teeth. On the other hand, a relatively porous polymer material such as noncross-linked polymethylmethacrylate has been found quite efficient from the standpoint of bonding the same to the enamel surface of a patient's teeth. This material would bond well with the surfaces of the patient's teeth and thus remain in place for extended periods of time. It has also been determined through patient reports and laboratory analysis that relatively porous polymer compositions have a tendency to become stained after a period of time and are not as resistant to abrasion as is desired for long lasting service. It is therefore desirable to provide a laminate dental veneer having the capability of efficient attachment to the enamel surfaces of the patient's teeth and which is also stain-resistant, chemical-resistant and resistant to erosion.
When noncross-linked polymer materials are employed for the manufacture of laminate dental veneers, the uniform color system thereof, though developing a generally pleasing appearance, does not develop natural characteristics of dental color and appearance. A natural tooth has a degree of translucency and certain intrinsic colors thereof reflect light and provide three-dimensional color characteristics. Color pigments are present in the enamel structure of a human tooth and the enamel is somewhat translucent. Light entering the translucent enamel is reflected, thus reflecting the enamel tooth color. Light waves penetrating the enamel also reflect the color characteristics of the dentin situated below the layer of translucent enamel. On visualizing a tooth therefore the intrinsic colors of the enamel and dentin are present and assist in providing the tooth with a three-dimensional physical appearance and color characteristics. Ideally, a laminate veneer should also have the capability of providing the tooth with a three-dimensional physical characteristic as well as a three-dimensional color characteristic involving the colors normally formed in the enamel and the dentin. With the uniform color system of the material from which laminate veneers have been composed, it is not possible to achieve an appearance significantly close to that of a natural tooth. It is therefore desirable to provide a laminate dental veneer having more nearly the characteristics, appearance and color of a normal human tooth.